In a variety of engine-powered vehicles, monitoring and diagnostic devices are employed to detect the presence of various undesirable operating conditions, such as overheating of the engine, low oil pressure, low fuel, and the like, and indicators are provided to warn the operator of such conditions. These instruments are typically connected to various sensors and switches for monitoring or controlling conditions on the vehicle via a wire harness and/or a communication link. In many applications, these instruments are also connected to electronic control systems, for example electronic engine controls, electronic transmission controls, and the like.
Most prior art systems have included dedicated instruments in which the functions and conditions of the vehicle to be monitored or diagnosed, as well as the particular sensors provided on the vehicle, are identified in advance. Therefore, the instruments are specifically designed for and hence "dedicated" to the monitoring or diagnosing of those particular vehicle functions and conditions in response to signals from pre-identified sensors. Accordingly, such "dedicated" instruments generally cannot be readily modified to accommodate different machines, different sensors and/or different conditions and functions. Rather, such instruments are generally limited to use with a particular vehicle type or model for which the instrument has been designed.
However, it is advantageous for these instruments to be usable in connection with many different machines. Lower costs will be achieved and less warehousing space will be required if a single instrument can be manufactured which can be used in many different applications. Similarly, service time is reduced if software changes are avoided when an instrument is moved from one machine to another.
Some prior art systems have provided for standardized monitoring systems that are usable in connection with a variety of machines, for example the system shown in U.S. Pat. Nos. 4,551,801 issued to Sokol on Nov. 5, 1985. While being an improvement over dedicated systems, this monitoring system is still relatively inflexible and requires the addition or subtraction of monitoring modules and the use of decals to indicate the parameters being shown by each display module.
In some situations the instrument also communicates sensor information to one or more external electronic controls. Since different data is required by different controls and in connection with different machines, it is desirable to reduce traffic on the communications link by communicating only information that is required by the controls on the particular machine to which the instrument is connected.
The present invention is directed to overcoming one or more of the problems set forth above.